Drug maker Alpine Immune Sciences (NASDAQ:ALPN) got a $4.9 billion buyout offer from Vertex Pharmaceuticals (NASDAQ:VRTX) after getting good news on a new drug.Povetacicept, an autoimmune drug, won a successful Phase 2 review from the Food and Drug Administration (FDA) for treating a rare kidney disease and will go into Phase 3 trial. Alpine stock rose 21% on April 10, and another 36% overnight, opening April 11 at $64.18 per share. More Than Kidneys?While Povetacicept is only being tested for a rare kidney ...